The average age of $6$ members of a family is $20$ years. If the age of a servant is included,the average age increases by $25\%$. What is the age (in years) of the servant?

Out of seven given numbers,the average of the first four numbers is $4$ and that of the last four numbers is also $4$. If the average of all the seven numbers is $3,$ then the fourth number is?

In a family,the average age of a father and a mother is $35 \text{ years}$. The average age of the father,mother,and their only son is $27 \text{ years}$. What is the age of the son (in $\text{years}$)?

Out of nine persons,$8$ persons spent $Rs. 30$ each for their meals. The ninth person spent $Rs. 20$ more than the average expenditure of all the nine. What was the total money spent by all of them (in $Rs.$)?

The average of the first $46$ natural numbers is:

The average temperature from Monday to Thursday is $48^{\circ} C$ and from Tuesday to Friday,the average temperature is $52^{\circ} C$. If the temperature on Monday is $42^{\circ} C$,what was the temperature on Friday in $^{\circ} C$?